Adding _int.to_str triples time to compile standard library

[jyasskin]

Before jyasskin/rust@684502b:
$ time ./rustboot -L . -shared -o libstd.dylib lib/std.rc
real 0m1.205s; 0m1.168s; 0m1.159s

After:
$ time ./rustboot -L . -shared -o libstd.dylib lib/std.rc
real 0m3.375s; 0m3.571s; 0m3.421s

This is with CFG_NATIVE=1. There must be something pathological in the compiler. A 40-line function shouldn't be able to triple the build time.

[graydon]

Yeah. I think I added a bit too much un-guarded logging in the past week. I'll do a profile-and-shave run on monday and should get it back down a ways.

[graydon]

Good news: found the source of pain. Bad news: will take a little bit of time to fix. On it this afternoon.

[graydon]

I think this is fixed enough to be tolerable for now. There is still a bit of a sore spot in the RA but it's nothing spectacularly non-local or non-linear like you were seeing. Let me know if you are feeling it slowing down again.

[graydon]

Er, for reference sake the commit that did most of the fixing was 3d69407.